Previously, the treatment of abdominal aortic aneurysms has involved using surgical grafts wherein the grafts are sutured into place. Conventional vascular grafts have long been used in humans and animals.
The treatment of abdominal aortic aneurysms requires a major surgical procedure to open the abdomen, excise the aneurysm sac and replace the vessel with a graft, which is sutured into place under direct vision. Many materials have been used to form the graft. At the present time this remains the preferred method of treatment for almost all abdominal aortic aneurysms.
Surgical graft materials such as flexible tubes of woven or knitted polyethylene terephthalate or porous polytetrafluoroethylene (PTFE) have previously been used. Grafts of biological origin have also been used; examples of these being fixed human umbilical or bovine arteries.
In the last few years, attempts have been made to reduce the extent of the surgical procedure by introducing these conventional, surgical grafts through the femoral arteries, passing them proximally, through the iliac arteries into the aorta and fixing them in place using endovascular stents, rather than sutures. These surgical grafts are large calibre devices which, even in their non-deployed state, are as large or even exceed the diameter of the iliac arteries through which they must pass. As the iliac arteries are often narrowed by, for example, atheromatous disease, the arteries may be damaged during introduction of the device.
More recently, interventional radiologists have attempted to improve on this concept using non-surgical graft material, catheters and endovascular stents to locate suitable vascular grafts or conduits onto the aortic aneurysm sac, from percutaneous punctures in the femoral arteries, requiring minimal surgical intervention. These techniques have become known as minimally invasive therapy.
A driving force to the development of the devices proposed in the present application has been the reduction in the size of the device when being inserted and also the reliability of the devices.
Although intraluminal devices are well-known in the field for the repair of inner linings for blood vessels or other body conduits, these previous types of devices are constructed, for example, from a thin layer of PTFE wrapped around a housing which is capable of expansion. Examples of such housings include self-expanding or balloon expandable-type devices comprising a mesh-like structure.
Due to the mesh-like structures used in previously known stent grafts, there is a minimum diameter to which the device can be reduced on its full contraction. On average, the minimum to which these devices can be reduced is 7 mm (21 French gauge) in diameter. There is therefore a limitation of these types of devices, for example, for use in babies, small children and old people where any amount of abrasion on the inner lining of the blood vessel during insertion of the stent graft may cause rupture of the vessel. It can also prove troublesome to expand these devices once inserted into the body. These types of grafts may also suffer from kinking which can result in the blocking of the passageway.
It is an object of at least one aspect of the present invention to mitigate one or more of the aforementioned problems and disadvantages of the prior art.
It is therefore an object of the present invention to provide a kink resistant device capable of forming a lining for blood vessels or other body conduits.